1. Field of the Invention
The present invention relates to a jet-propulsion watercraft which ejects water rearward and planes on a water surface as the resulting reaction. More particularly, the present invention relates to a jet-propulsion watercraft that can maintain steering capability even when the throttle is operated in the closed position and propulsion force is thereby reduced.
2. Description of the Related Art
In recent years, so-called jet-propulsion personal watercraft (PWC) have been widely used in leisure, sport, rescue activities, and the like. The personal watercraft is configured to have a water jet pump that pressurizes and accelerates water sucked from a water intake generally provided on a bottom of a hull and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.
In the personal watercraft, in association with a steering handle of a general bar type, a steering nozzle provided behind the outlet port of the water jet pump is swung either to the right or left, to change the ejecting direction of the water to the right or to the left, thereby turning the watercraft to the right or to the left.
A deflector is retractably provided behind the steering nozzle for blocking the water ejected from the steering nozzle. The deflector is moved downward to deflect the ejected water forward, and as the resulting reaction, the personal watercraft moves rearward. In some watercraft, in order to move rearward, a water flow is formed so as to flow from an opening provided laterally of the deflector along a transom board to reduce the water pressure in an area behind the watercraft.
In the above-described personal watercraft, when the throttle is moved to a substantially fully closed position and the water ejected from the water jet pump is thereby reduced, during forward movement and rearward movement, the propulsion force necessary for turning the watercraft is correspondingly reduced, and the steering capability of the watercraft is therefore reduced until the throttle is re-opened.
To address the above-described condition with a mechanical structure, the applicant disclosed a jet-propulsion personal watercraft comprising a steering component for an auxiliary steering system which operates in association with the steering handle in addition to a steering nozzle for the main steering system in Japanese Patent Application No. Hei. 2000-6708.
Also, for the purpose of achieving a lightweight watercraft, the applicant disclosed a jet-propulsion personal watercraft in Japanese Patent Application No. Hei. 2000-173232, in which a sensor is adapted to detect a throttle-close operation, a steering operation, or the like, and an engine speed is increased according to the detection.
The present invention addresses the above-described condition, and an object of the present invention is to provide a jet-propulsion watercraft that can maintain steering capability according to the cruising speed thereof even while an operation which closes the throttle (hereinafter referred to as xe2x80x9cthrottle-close operationxe2x80x9d) is performed and the amount of water ejected from a water jet pump is thereby reduced.
According to the present invention, there is provided a jet-propulsion watercraft comprising: a water jet pump that pressurizes and accelerates sucked water and ejects the water from an outlet port provided behind the water jet pump to propel the watercraft as a reaction of the ejecting water; an engine for driving the water jet pump, the engine being provided with a throttle valve; a steering operation means that operates in association with a steering nozzle of the water jet pump; a throttle lever for being operated to open/close the throttle valve; a first connecting member for connecting the throttle lever to the throttle valve; and a second connecting member for connecting the steering operation means or a rotational shaft of the steering operation means to the throttle lever so as to operate the throttle lever to cause the throttle valve to be opened according to an steering operation of the steering operation means.
In a jet-propulsion watercraft of the present invention, even while the throttle-close operation is performed but the steering operation means is operated, the second connecting member operates the throttle lever to a direction to open the throttle valve according to the steering amount or a rotational angle of the rotational shaft according to the steering. Since the engine speed is increased according to the amount of the throttle lever operation, the water sufficient to turn the watercraft is ejected from the water jet pump, that is, a sufficient propulsion force is thereby obtained. Consequently, the steering capability can be maintained even while the throttle-close operation is performed.
Herein, control for increasing the engine speed is referred to as xe2x80x9csteering assist mode controlxe2x80x9d, and the xe2x80x9cthrottle-close operationxe2x80x9d is to be understood to signify an operation performed to bring the throttle toward a closed position by a predetermined amount or more.
The second connecting member may be constituted by a push-pull cable. One end portion of the cable is connected to a portion protruded directly or indirectly on an outer peripheral face of the rotational shaft of the steering handle. Since the one end portion of the push-pull cable is thus connected to the portion protruded on the outer peripheral face of the rotational shaft, the rotational angle of the rotational shaft according to the steering operation can be converted into the movement of the cable at a greater rate. Also, since advancement/retraction of the other end portion of the operated cable operates the throttle lever to cause the throttle to be opened, the second connecting member can be constituted by a simple general member.
As the second connecting member described above, a pair of push-pull cables are provided. These cables are pushed and pulled toward opposite directions with respect to each other according to the rotation of the rotational shaft. One of the other end portions of these cables, i.e., the end portions of the cables connected to the throttle lever, is advanced/retracted to operate the throttle lever to cause the throttle to be opened. When the steering operation means is steered to the right or to the left, the throttle lever can be operated to cause the throttle to be opened regardless of the steering direction.
According to the present invention, there is also provided a jet-propulsion watercraft comprising: a water jet pump that pressurizes and accelerates sucked water and ejects the water from an outlet port provided behind the water jet pump to propel the watercraft as a reaction of the ejecting water; an engine for driving the water jet pump; a steering operation means that operates in association with a steering nozzle of the water jet pump; a first air-fuel mixture supplying system for supplying an air-fuel mixture to the engine through a first air-fuel mixture supplying passage, the first air-fuel mixture supplying system being provided with a first throttle valve; a second air-fuel mixture supplying system for supplying an air-fuel mixture to the engine through a second air-fuel mixture supplying passage; and a throttle lever for performing an open/close operation of the first throttle valve, and the second air-fuel mixture supplying system is adapted to increase the air-fuel mixture supplied to the engine during the operation of the steering operation means, thereby increasing the engine speed.
According to the jet-propulsion watercraft of the present invention, while the throttle-close operation is performed, and thereby the air-fuel mixture is not supplied from the first air-fuel mixture supplying system generally provided in the engine, the air-fuel mixture is supplied to the engine from the second air-fuel mixture supplying system while the steering operation means is operated. Thereby, the engine speed is increased. Therefore, the water sufficient to turn the watercraft is ejected from the water jet pump, that is, a sufficient propulsion force is obtained. Consequently, steering capability can be maintained even while the throttle-close operation is performed.
Specifically, the fuel-air mixture is supplied from the second air-fuel mixture supplying system as follows. The watercraft comprises a first connecting member for connecting the throttle lever to the first throttle valve; and a second connecting member for connecting the steering operation means or a rotational shaft of the steering operation means to the second throttle valve, to cause the second throttle valve to be opened according to an steering operation of the steering operation means. In this case, according to the steering amount or the rotational angle of the rotational shaft according to the steering, the second connecting member causes the throttle valve of the second air-fuel mixture supplying system to be opened. With this configuration, the air-fuel mixture supply can be increased according to the position of the throttle valve.
The second air-fuel mixture supplying system may be provided at a position in the air supplying passage to the first air-fuel mixture supplying system and in the first air-fuel mixture supplying passage. In this case, the second air-fuel mixture supplying system may be connected to the position directly or indirectly through a connecting passage. When the second air-fuel mixture supplying system is indirectly connected, the degree of freedom at which the system can be mounted is increased and the mounting space for the whole engine including the system can be reduced.
Also, the first air-fuel mixture supplying passage may be provided with a passage that bypasses the throttle valve in the first air-fuel mixture supplying system, and the second air-fuel mixture supplying system can be provided in this bypass passage.
The second air-fuel mixture supplying system may be provided on the side of the first air-fuel mixture supplying system with respect to the engine. Thereby, the predetermined connecting passage connecting the second air-fuel mixture supplying system and the first air-fuel mixture supplying passage can be shortened. Consequently, since the fuel-air mixture is quickly supplied into the engine from the second air-fuel mixture supplying system, the response of the engine to the air-fuel mixture supply from the second air-fuel mixture supplying system can be improved.
A check valve may be provided in a fuel supplying passage for supplying fuel to the second air-fuel mixture supplying system from a fuel supplying source, to flow the fuel only toward the second air-fuel mixture supplying system from the fuel supplying source. Thereby, back flow of the fuel due to the vibration of the engine or the like can be prevented and the air-fuel mixture can be stably supplied from the second air-fuel mixture supplying system to the engine.
A liquid entry prevention means may be provided at a supply source side end of the air supplying passage of the second air-fuel mixture supplying system, for preventing liquid (i.e., water) from being mixed into a supplying air. Since the entry of the water into the engine is prevented, the engine can stably operate. The liquid entry prevention means may be, for example, an air-intake box (or air cleaner box) provided in the first air-fuel mixture supplying system. In this case, since there is no need for an additional member mounted on the watercraft as the liquid entry prevention means, a lightweight watercraft can be achieved.
The first air-fuel mixture supplying system and the second air-fuel mixture supplying system may comprise a common fuel supply source. Thereby, the lightweight watercraft can be also achieved.
The first air-fuel mixture supplying system and the second air-fuel mixture supplying system may be located at substantially the same position in the vertical direction of the watercraft. Thereby, for example, when a common pressure regulator is employed to supply the fuel to both air-fuel mixture supplying systems, the pressures at which the fuel is supplied to these air-fuel mixture supplying systems become equal. Consequently, the air-fuel mixture can be stably supplied to the engine from these air-fuel mixture supplying systems.
The second air-fuel mixture supplying system is mounted to a position of the watercraft that is within a vibration system independent of a vibration system of the engine. Thereby, the second air-fuel mixture supplying system is not directly subjected to the vibration of the engine, and therefore, the air-fuel mixture can be stably supplied to the engine from the second air-fuel mixture supplying system.
When the engine is a multiple-cylinder engine, the air-fuel supplying passage of the second air-fuel mixture supplying system may be branched according to the number of cylinders, and the air-fuel mixture is supplied to the respective cylinders through the branched air-fuel mixture supplying passages (this may be including the predetermined connecting passages). Thereby, the similar state (e.g., density or atomized state) air-fuel mixture can be easily supplied to the plurality of cylinders. Also, since the air-fuel mixture can be supplied to the plurality of cylinders by using the single second air-fuel mixture supplying system, the lightweight watercraft can be achieved.
The lengths of the branched connecting passages are set substantially equal. Thereby, the uniform air-fuel mixture can be easily supplied to the respective cylinders.
The fuel-air mixture may be also supplied from the second air-fuel mixture supplying system as follows. The watercraft may further comprise: a steering position sensor for detecting a predetermined steering position of the steering operation means; and an electric control unit, and the electric control unit is adapted to execute control to increase the air-fuel mixture being supplied to the engine from the second air-fuel mixture supplying system, for example, by executing control to open the throttle valve of the second air-fuel mixture supplying system, while the steering position sensor is detecting a predetermined steering position.
The steering position sensor may be constituted by a proximity switch provided to a rotational shaft of the steering operation means.
The throttle valve of the second air-fuel mixture supplying system is opened by supplying electric power to a solenoid adapted to drive the throttle valve to be opened/closed, by the control of the electric control unit. Thereby, the second air-fuel mixture supplying system can be electrically controlled.
The personal watercraft may further comprise a throttle-close operation detecting means for detecting a close-operation of the throttle valve in the first air-fuel mixture supplying system, and the engine speed can be increased while the steering operation is detected by the steering position sensor and the throttle-close operation is detected by the throttle-close operation detecting means.
The throttle-close operation may be detected by the throttle position sensor or the engine speed sensor and the throttle position sensor. The throttle-close operation detecting means is not limited to these and may be a detecting means provided in a mechanism connecting the throttle lever to the throttle valve of the first air-fuel mixture supplying system, for detecting an operation of the mechanism at the throttle-close operation of the throttle valve. Also, it is possible to use a sensor for detecting an air-intake pressure and an air-intake amount of the supplying air to the engine. When the air-intake pressure is used, the relationship between the air-intake pressure and the engine speed is obtained in advance, for detecting the throttle-close operation only when the engine speed is low.
The above and further objects and features of the invention will more fully be apparent from the following detailed description of the accompanying drawings.